Electric switch



May 16, 1933.

T. s. BINDSCHEDLER 1,908,881

' ELECTRIC SWITCH Filed Aug. 10, 1951 2 Sheets-Sheet 1 INVENTOR V 53 gnaw/ore fiBindsched/er m M w/ 0m, %nmf ATTORNEYS y 1933- T. s. IBINDSCHEDLER 1,908,881

ELECTRIC SWITCH Filed Aug. 10, 1951 2 Sheets-Sheet 2 30 Fig. 4-.

INVENTOR mwdore 5. Bindscfied/er ATTORN EYS little load on the keys.

Patented May 16, 1933 "UNITED STATES PATENT oi'FlcE THEODORE S. BINDSCHEDLE-R, OF IJETROIT, MICHIGAN, ASSIGNOR T BURROUGHS ADDING MACHINE COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF HIGH- ELECTRIC SWITCH Application filed. August 10, 1931; Serial No. 556,132.

This invention relates to an electric switch for use on appliances where a very delicate force is available for opening andclosing the switch.

Certain calculating machines have recently been developed in which the motor is normally inactive, that is, it is not energized. When one of the keys of the machine is depressed the motor circuit is closed and the machine operated. The keys of a machine of this type must be depressible with a light or easy key touch and, where depression of the keys closes the motor circuit, it is essential that the closing of the switch impose very While it is possible to close the switch by a very delicate force, the difficulty" is that, when the switch is so closed and opened, the tendency is for the contact to be poor so that arcing soon destroys the eiiectiveness of the switch. The present invention has been directed to the" solution of this problem.

The general object of the invention is to provide an improved electric switch that can be closed by a very delicate force and which at the same time will keep the switch contacts clean so as to give them long life.

A more particular object is to provide an improved electric switch in which contacts are brought together with a wiping action.

A further object is to provide an improved electric switch in which the electric current is not passed through any of the pivots of the switch.

Other objects and advantages of the invention will appear from the following specification and drawings.

An embodiment of the invention is shown in the accompanying drawings in which:

Figure 1 is a partial right'side sectional elevation of a calculating machine showing an application of the switch to such a machine. v

Fig. 2 is a perspective of the switch with the parts in normal position.

Fig. 3 is a detailed plan view of the switch in closed position, some of the parts being broken away toshow others more clearly. Fig. 4 is a View similar to Fig. 3 with the switch moved toward open position, but before the contacts have separated.

Fig. 5 is a view similar to Fig. 4 with the switch completely opened.

The invention is shown applied to a calculator having a series of depressible amount keys having stems 11 that operate in slots 12 in a slidable bar 13 urged to the left, as viewed in Fig. 1, by a spring 16. The machine has a plurality of banks of keys with a 'bar 13 for each bank. Each bar 13 has a downwardly extending projection 17 positioned' behind a bail 18 pivoted at 19. This bail has a downwardly extending projection 20 for controlling the switch that starts and stops the motor.

When one of the amount keys is depressed,

its bar 13 is cammed to the right as viewed 1n Fig. 1 against the tension of the spring 16. This swings the bail 18 counterclockwise and moves the projection I20 away from the switch controlling arm to allow the switch to close under the action of its spring as will be later described.

Referring to Fig. 2, the switch is mounted upon a base which may be supported in any suitable manner, the base in the embodiment shown being a portion of the bracket that supports the electric motor 31 (Fig. 1).

Mounted on the base is a terminal 32 supporting a stationary switch contact member 33. This terminal is completely insulated froin the base by suitable insulating washers 34 and,\on the underside, it has suitable binding screw connections 35 (Fig. 1) to which one terminal 36 of the motor circuit may be connected.

A movable switch contact 40 is carried by a movable unit including an arm 41 and a controlling member 42. The left hand end of arm 41 as viewed in Fig. 2 is yoke-shaped at 43 and the yoke-shaped portion is pivoted at 44 to the yoke-shaped portion 45 of the controlling member 42. The arm 41 has only a limited movement relative to the controlling member 42 by reason of the fact that the yoke' 43 of arm 41 contacts the edges of yoke 45 of member 42 after arm 41 moves slightly in either direction on its pivot.

The yoke-shaped portion 45 of the controlling member 42 is pivoted on a stud 46 suitably secured to the base 30 and insulated therefrom by washers 47. The left-hand end of the Controlling member as viewed in Fig. 2

, is insulated at 48 and this insulated portion is the part that is engaged by the downward-- ly-extending projection 20 which normally holds the controlling member against movement toward switch-closing position.

- A second switch terminal 50 is mounted upon the base plate 30 and suitably insulated therefrom by washers 51. This terminal is also provided with suitable binding screws 52 (Fig. 1) for attaching a conductor 53 of the motor circuit.

Provision is made for urging the unit in eluding the arm 41 and controlling member 42 in a counterclockwise direction toward switch-closing position and provision is also made for urging the arm 41 counterclockwise relative to controlling member 42, a single spring being employed to accomplish both results in the embodiment of the invention illustrated.

Fixed to the second terminal 50 is a spring 54 which extends rearwardly from the terminal and then extends approximately at right angles through the yoke-shaped portion 45 of the controlling member 42, the right angled portion being designated 55 in Fig. 2. The spring is then doubled back to provide another portion 56 which is attached by a rivet or stud 57 to the yoke 43 of the arm 41. The shape and resiliency of the spring is such that, when attached to terminal 50, it acts to urge the unit comprising the controlling member 32 and arm 41 in a counterclockwise direction and also to urge the arm 41 counterclockwise on its pivot 44.

When one of the keys 10 is depressed, (Fig. 1) the slide 13 is moved to the right, the bail 18 is rocked counterclockwise and the PIOJGC- tion 20 moves away'from the insulated end 48 of the controlling'member 42. Depression of the key does not actuate the switch but releases it for actuation by its own spring. No direct load is placedmn the keys, but this does not mean that the spring that tends to close the switch can be made strong because the switch must be opened again by the projection 2O engaging the controlling. arm 42 and pulling the switch open against the tension of the switch spring 54. This means that the spring 16 whichtends to urge the slide 13 to the left must be stronger than the switch spring 54. If the switch spring were made strong, the spring 16 would have to be stronger. It will be remembered, however, that depression of the keys 10 must move the slide 13 against the tension of spring 16. Consequently, in order to have a light key depression the spring 16 must be light. This means that the switch spring 54 must be still lighter. In the switch shown the spring 16 is light as is also the spring 54 which makes the key depression very easy.

The operation of the switch is somewhat diflicult to explain owing to the novel spring action that takes place. It will be best understood by starting with the switch in closed position, although the switch illustrated in the present case is normally open.

When the switch is closed, as illustrated in Fig. 3, the unit carrying the movable switch contact 40 is urged to this closed position by the spring 54. The spring exerts an urging action on the yoke 43 that is connected to yoke 45 and thereby urges yoke 45 and controlling member 42 counterclockwise as viewed in Fig. 3. The urging action against the unit as a whole is suflicient to cause the arm 41, which is apart of the unit, to be swung slightly clockwise on its ivot as illustrated in Fig. 3, the movement 0' the arm being limited in this direction by the engagement of the yoke 43 with the edges of the yoke 45.

As the controlling member 42 is swung clockwise to open the switch, the yoke 45 moves about its pivot 46. This carries the pivot 44 through an arc of which the center is pivot 46. Referring to Figs. 3 and 4 it will be observed that, during this movement, the are through which the pivot 44 swings is so small, that, for all practical purposes it is substantiallycoincident with the longitudinal plane, illustrated by line 60GO, of the portion of the arm 41 that carries the switch contact 40. In other words, the pull on the arm 41 is substantially a longitudinal pull. As the parts move in this direction, the tendency would be, if arm 41 were rigidly fixed to yoke 45, for arm 41 to swing away to separate contact 40' from contact 33. But arm 41 is pivoted to yoke 45 and is urged counterclockwise on its pivot by spring 54. As a result, when yoke 45 swings clockwise as'above explained, the arm 41 with its yoke 43 swings counterclockwise under the influence of spring 54 and contacts 40 and 33 are maintained in engagement. During this movement, however, arm 41 and yoke 43 mustmove with yoke 45 which they do but the move ment is a longitudinal one causing contact 40 to slide on contact 33 from the position of Fig. 3 to that of Fig. 4. If arm 41 with its yoke 43 were rigidly fixed to yoke 45 the movement of. yoke 45 would tend to flex the portion 56 of the spring 54 in the manner shown in Fig. 5. However, since the arm 41 with its yoke 43 is pivoted to the yoke 45 the portion 56 of the spring does not flex noticeably. Instead, the portion 55 flexes so that the spring moves from the position of Fig. 3 to that of Fig. 4. The position of the spring relative to the center line through pivot 46 illustrates the movement.

After the parts reach the position of Fig. 4, the arm 41 cannot move any farther clockwise'owing to the engagement of the edge When the switch is closed the reverse action takes place. The unit is rocked counterclockwise from the position of Fig. 5 to that of Fig. 4, during which movement the portion 56 of the spring begins to straighten out and the contact 40 is brought into engagement with'the contact 33 in the Fig. 4 position. When contact 40 engages contact 33 the arm 41 cannot move any farther counterclockwise with the unit with the result that the continued movement of controlling memvber 42 in a counterclockwise direction about its pivot 46 causes the arm 41 to be swung clockwise from the Fig. 4 to the Fig. 3 position, during which movement the contact 40 slides on contact 33 from the Fig. 4 to the Fig. 3 position. The movement of the spring in this closing movement is the reverse to what was explained for the opening of the switch. In actual practice the movements take place in combination so that they blend together into one movement. When the parts reach the Fig. 3 position the controlling member 42 cannot move any farther counterclock-- wise because the edges of its yoke 45 engage the yoke 43 of member 41 which is blocked against further movement by the engagement of the contact 40 with contact 33.

The switch is thus opened and closed with a wiping action between the contacts 40 and 33 that tends to keep them clean. This action is secured by the use of a single spring acting in the novel manner described.

In addition to performing the two functions mentioned above, the spring 54 also carries the current from one terminal to the other and this is accomplished without passing the current through any of the pivotedv portions of the switch. The current passes from the terminal 32 through the contacts 33and 40, through the arm 41, through the spring 565554 to the second terminal 50. This avoids the objectionable passage of current through moving sw-itdh parts which may make poor contacts and which would pit and bum so that the switch might become inoperative.

I claim:

1'. A switch having a stationary contact member, a pivoted controlling member, an arm pivoted to said controlling member carrying a switch contact, means urging said controlling member toward switch-closing position, said means also urging said arm toward switch-closing position relative to said controlling member whereby, when said controlling member is moved to close and open said switch, said contacts are closed and opened with a wiping action, and means between said controlling member and said arm predetermining the relative positon of the latter with respect to said stationary contact in switch closing position of said arm.

2. A switch having a stationary switch contact, a pivoted controlling member, an arm pivoted to said member carrying a switch contact, said arm having a limited pivotal movement relative to said member in its switch closing movement, and a springurging said member toward switch closing position, said spring also urging said arm toward and holding it in a predetermined switch closing position relative to said member, whereby when said member is moved to open and close the switch, said contacts are opened and closed with a wiping action.

3. A switch having a stationary switch contact, a pivoted controlling member extending substantially at right angles to the plane of the surface of said switch contact, an arm pivoted to said member and extending at right angles thereto, said arm carrying a switch contact and having a limited movement relative to said member, and means urging said arm about its pivot toward switch closing position whereby, when said member is moved to open and close said switch, said contacts are opened and closed with a wiping action.

4. An electric switch having a stationary switch contact, a pivoted controlling member, an arm carrying a movable contact, said arm having a limited pivotal movement connection with said controlling member and. extending substantially at right angles thereto, said member and arm being located relative to said stationary switch contact so that, when said switch is closed, a line through the pivots of said member and arm issubstantially at right angles to the longitudinal axis of said arm, and means urging said arm about its pivot toward switch closing position, whereby, when said controlling member is moved to open said switch, the arm carrying said movable contact is first moved longitudinally to wipe said movable contact over said stationary contact and is then swung away to separate said contacts.

5. An electric switch having a stationary switch contact, a pivoted controlling member, an arm carrying a movable switch contact. said arm being pivoted to said controlling member,said arm and said member being located so that a line through their pivots is substantially at right angles to the longitudinal axis of said switch arm, anda spring urging said controlling member toward switch closing position and said switch arm toward switch closing position relative to said member whereby, when said controlling membcr is moved to open and close the switch,said contacts are opened and closed with a wiping action. 1 f

and the other end connected to a stationary support, the base ofv said U-shaped spring being on the side of the pivot of said controlling member opposite to the pivot of said.

arm whereby, when said controlling member is moved to open and close the switch, said switch contacts are opened and closed'with a Wiping action.

7. A switch having a stationary switch contact, a pivoted controlling member, a switch arm pivoted to said controlling member and carrying a switch contact, said arm being limited in its pivotal movement relative to said member, said member and arm being located relative to said stationary switch contact so that a line between their pivots is substantially at right angles to the plane of said stationary switch contact, and a spring having one of its ends connected to a stationary support on one side of said arm, said spring extending substantially parallel to said arm and then at right angles past the pivoted end of said arm and the pivot of said controlling member, said spring then extend ing around the pivot of said controlling member and being connected to said arm to urge said arm about its pivot toward switch closing position, said spring being out of contact with the other switch parts except at its said points of connection and acting to urge said controlling member toward switch closing position.

8. A switch having a switch terminal pro vided with a stationary contact member, a pivot-ed control member, an arm pivoted to said control member and carrying a switch contact, said arm having a limited pivotal movement relative to said control member, a second switch terminal, and a spring connected bothlmechanically and electrically to said switch terminal and to said arm acting to urge said .arm about its pivot-toward switch-closing position and acting to urge said control member about its pivot toward switch-closing position, said spring being out of contact with the other switch 'parts' except at its said points of connection and serving as the sole carrier of electric current from said switch terminal to said contactcarrying arm.

9. A switch having a terminal provided with a stationary switch contact member, a pivoted gontrol member normally restrained against movement toward switch-closing position, an arm pivoted to said control member and carrying a movable switch contact, said arm having a limited pivotal movement relative to said controlling member, a second switch terminal, and a spring connected both mechanically and electrically to said second switch terminal and to said arm, said spring being out of contact with the other switch parts except at its said points of connection and urging said controlling member toward switch-closing position and said arm about its pivot toward switch-closing position.

10. A switch having a stationary contact member, a pivoted controlling member, an arm pivoted to said controlling member,

-means limiting the movement of said arm ative to said controlling member within the limits of said limiting means toward switch closing position to engage said stationary and arm-carried contacts.

11. The combination in a switch mechanism having a stationary contact, of a pivoted controlling member, an arm having a contact engageable with said stationary contact pivoted to said controlling member between the ends thereof and extending away therefrom at substantially right angles, spring means urging said controlling member toward a switch closing position, and likewise said arm, means for moving said controlling member and likewise said arm toward a switch-opening position, and means betweenisaid arm and controlling member limiting relative swing movement thereof during both said switch-opening and switchclosing movements.

12. In structure of the class described having a stationary contact, a controlling member pivotally supported at one end, an arm er end engagea-ble with said stationary contact, said arm and member being positioned at substantially right angles with respect to each other, and means urging said member and arm toward a switch closing position including a terminal post and a spring secured at one end to said post and at its other end to said arm, said spring being shaped to extend from said post substantially parallel with said arm then substantially parallel with said member and then reversel curved into substantially parallelism with said member. v

13. In structure of the class described having a stationary contact, a controlling member pivotally supported at one end an arm pivotally connected at one end to said member and having a contact element at its other end engageable with said stationary contact, said arm and member being positioned at substantially right angles with respect to each other, and means urging said member and arm toward a switch closing position including a terminal post and a spring secured at one end to said post and at its other end to said arm, said spring being shaped to extend from said post substantially parallel with said arm thenv substantially parallel with said member and then reversely curved into substantially parallelism with said member, said spring serving as an electrical conductor and;engaging the switch parts only at its said points of connection.

In testimony whereof, I have subscribed my name."

THEODORE S. BINDSGHEDLER. 

